We have isolated several single gene Drosophila mutants which fail to learn an olfactory discrimination avoidance task, although they behave normally in other respects. (We also have another mutant, amnesiac which shows abbreviated memory). We are currently measuring their learning performance in other situations; including reward-mediated tests. We are also looking for abnormal patterns of 2-deoxyglucose, and for biochemical abnormalities in monoamine transmitter synthesis, monoamine-stimulated cyclic nucleotide synthesis, and membrane protein phosphorylation in the learning mutants.